This study is to evaluate the baseline diurnal dysregulation of circadian rhythms in persons with depression compared with normal controls as indicated by onset of melatonin acrophase at night (DLMO). The effects of sleep deprivation (SD) on circadian rhythms in depressives and normal controls as measured by the timing of DLMO and amplitude of the nocturnal melatonin peak. In addition we will continue our work on the effects of SD on the response to antidepressant medications.